Effect of foliar‐applied gibberellins and soil‐applied paclobutrazol on fruit quality at harvest and during storage of ‘Braebum’ apples growing under a high‐density planting system

Abstract Five‐year‐old ‘Braeburn/MM.106’ apple ( Malus domestica Borkh.) trees growing under a high‐density (10 000 trees/ha) planting system were treated with paclobutrazol (PBZ) as a soil drench at 250 mg(a.i.) per tree in August 1993. Gibberellin (GA), GA 3 or GA 4 , was sprayed on vegetative buds at 0, 10, or 100 |jg per bud at three times between 22 November and 22 December 1992 (before PBZ treatment), or on the same dates in 1993 (after PBZ treatment). Apples harvested from the experimental trees in 1994 and 1995 were evaluated for fruit quality at harvest and during 90 days of storage at 10°C. Time of GA 3 or GA 4 application did not affect fruit quality at harvest. PBZ generally increased mean fruit weight the year after and then decreased 2 years after PBZ application. Fruit L/D ratio was decreased, °Brix values and fruit flesh firmness were generally increased with PBZ application to the trees. However, the effects were minor. The addition of GA to PBZ treated trees generally reversed the effects of PBZ. GA 4 was more effective than GA, in increasing fresh weight and L/D ratio. After 90 days of storage duration flesh firmness was reduced as an average from 8.4 to 5.2 units, °Brix values were increased as an average from 12.9 to 13.2, and average weight loss reached 13 g/fruit. Time of G A application, PBZ, or GA did not modify the effects of storage at 10°C.